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Could someone please identify these rocks? Hoping to use them in a saltwater aquarium

enter image description here

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closed as off-topic by user12525, trond hansen, Fred, arkaia, Erik Sep 6 at 20:58

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions about rock identification requests are off-topic. For more information, see the announcement on meta." – Community, trond hansen, Fred, arkaia, Erik
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Please improve your question by reading this answer and editing your question with more information. $\endgroup$ – mkennedy Jan 2 '18 at 20:39
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Three layered ones look like either sandstone or limestone with a bit of iron oxides. You can put several droplets of acid and check if they fizz. If they do, that is limestone, but I have seen limestone in that colour only once and think that is more likely to be sandstone.

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